The patient is a 59-year-old female with multinodular goiter with compressive symptoms, in addition to primary hyperparathyroidism, who underwent total thyroidectomy and excision of a presumptive parathyroid adenoma two years earlier, at a referring institution. Her goiter was extremely large (over 300 gms), and her exploration was described as difficult. After several intraoperative biopsies of 3 parathyroid glands, the operative team excised a suspected parathyroid adenoma. Postoperatively, her calcium level remained high (in the 11.5 range), and a sestamibi scan obtained on postoperative day 2 revealed increased uptake in the left superior mediastinal area. Her parathormone level also remained elevated (95), and she was diagnosed with persistent primary hyperparathyroidism. Her endocrinologist referred her to a 2nd tertiary care facility, who initiated localization studies.